This is a randomized double-blind, placebo-controlled, within-subjects trial of repeated doses of cocaine which is conducted to evaluate pharmacokinetic, physiological and behavioral effects of simultaneous consumption of the substances over time in a paradigm that more closely approximates use in the population at risk. The study is ongoing and will continue with the goal of reaching the sample size proposed for the study (28-14 men and 14 women). To date 8 subjects (4 men and 4 women) have completed the study without adverse event. We continue to actively recruit and enroll into this study. An interim data analysis will be conducted when 10 subjects have completed the study.